Folding paperboard carton flap locking construction



July 3, 1956 R. E. VAN ROSEN ETAL FOLDING PAPERBOARD CARTON FLAP LOCKING CONSTRUCTION Filed June 30, 1953 1 m mm m %m M M M M a 2 b v July 3, 1956 R. E. VAN ROSEN ET AL fi fl FCLDING PAPERBOARD CARTON FLAP LOCKING CONSTRUCTION Filed June 30, 1953 2 Sheets-Sheet 2 IN VEN TORS Rofier/E 16121 1 05612 BY Que/152A ,Mamzfzza W v W United States Patent FOLDING PAPERBOARD CARTON FLAP LOCKING CONSTRUCTION Robert E. Van Rosen, New York, N. Y., and Guelfo A. Manizza, Quaker Hill, Conn., assignors to Robert Gair Company, llnc., New York, N. Y., a corporation of Delaware Application June 30, 195-3, Serial No. 365,032

2 Claims. (Cl. 229-34) The invention relates to a locking construction for infolding end flaps of folding paperboard cartons.

Summary By our invention we provide, in a folding paperboard carton having a main panel, side wall panels con nected to the main panel and an infolding end wall panel with an adjoining locking flap approximately fitting into the corner of the set up carton, the fold lines between the main and side wall panels having transverse cut lines adjacent the corners of the locking flap in locking position, said fold lines having prescored portions terminating at said transverse cut lines. Thus the fold lines are formed in part by scoring the paperboard stock but have sections free of scoring.

The principal advantage of this construction is that when the carton is set up, the corners of the locking flap engage the bulges which form in the scoring at the intersection of the fold lines with said transverse cut lines when the side walls are erected. This construction is applicable to many types of infolding end wall cartons and covers. It may be applied, for example, to both bottom Section and cover section of hinged cover cartons, or to one or both of the infolding end flaps of a separate carton body, or of a separate cover.

in one of the specific forms which we will describe, the section of the fold line which is free of scoring is provided with a longitudinal cut line terminating at the aforesaid transverse out line. in another form a pair of spaced transverse cut lines is provided, and there is either an unscored portion between these out lines, or the section of the fold line which lies between the transverse cut lines is free of scoring but may be provided with a longitudinal out line terminating at the respective transverse cut lines.

Our locking construction can be produced in the operation of cutting and scoring the blank. All that is required is the elimination of a part of one or more of the rules of the cutting and creasing die, and the provision of one or more small knives to form the transverse cut lines as aforesaid. in the completed carton as set up for use, the locking construction is so inconspicuous as hardly to be noticeable. indeed, looking at the inside of the box or cover, the locking construction is virtually invisible.

Description in the drawings we have illustrated the application of our invention to one of the common forms of hinged cover box in accordance with what we consider to be its est embodiment.

Fig. l is a face view of the blank from which the carton is formed, viewed from the side which will be the inside of the carton when set up for use.

Fig. 2 is a detail perspective view looking into one of the inside corners of the cover of the box partially set up from the blank of Fig. 1.

Fig. 3 is a similar view after the cover has been fully set up for use.

Fig. 4 is a detail perspective view looking into one of 2,753,103 Patented July 3, 1956 the inside corners of the bottom of the box partially set up from the blank of Fig. 1.

Fig. 5 is an enlarged detail cross-sectional view taken as indicated at 5-5 in Fig. 1.

Fig. 6 is an enlarged detail cross-sectional view taken as indicated at 66 in Fig. 1.

Fig. 7 is an enlarged detail cross-sectional view taken indicated at 7-7 in Fig. 4.

Fig. 8 is an enlarged detail cross-sectional view taken as indicated at 88 in Fig. 4.

Fig. 9 is a partial view of a modified form of carton blank.

Fig. 10 is a detail perspective view looking into one of the inside corners of the cover of the box partially set up from the blank of Fig. 9.

In the preferred construction illustrated, the blank has a bottom section 11 and cover section 12. The bottom section comprises main panel 13 and panels to form side walls 14 and end wall 15. Similarly, cover section 12 comprises main panel 16 and panels to form side walls 17 and end wall 18. The main panels 13, 16 are joined by a common end wall panel 19. Side walls 14 and 17 are joined by foldable webs 20. Flaps 21 and 22 extend from the bottom and cover side walls 14 and 17 re spectively. End wall panels 15 and 18 have extensions forming infolding end wall panels 23 and 24 respectively with adjoining locking flaps 25 and 26 respectively. The several panels, flaps and webs of the blank are defined by score lines about which folding occurs during the operation of setting up the box. Except for the score lines 27 and 23, the score lines are conventional and require no description for the carton manufacturer beyond that provided by their clear indication in Figs. 1 and 9.

The fold lines formed in part by score lines 27 each have a section free of scoring, this section terminating in a transverse cut line 29 which is adjacent a corner of the locking flap 25 when the latter is in locking position in the carton as set u for use. Thus it will be seen that the fold lines between main panel 13 and side wall panels 14 have pre-scored portions 27 terminating at the transverse cut lines 29. In the bottom section of the particular carton construction shown in Fig. 1, the scoring is continued at 31 between the section which is free of scoring and the corners of the panel 13. Also, in this particular con struction, the portion which is free of scoring is provided with a longitudinal out line 32 terminating at the transverse cut line 29.

Similarly, the fold lines between main panel 16 and side wall panels 17 of the cover section have prescored portions 28 terminating at the transverse cut lines 33. Beyond cut lines 33 the fold lines here are free of scoring all the way to the corners of panel 16.

Reference is now made to Fig. 2 which is a detail perspective view looking into one of the inside corners of cover section 12 as partly set up, the flaps 22 infolded, and side and end walls 17 and 18 erected, but before the end wall panel 24 has been infolded. It will be observed that the erection of side wall 17 has produced a bulge 34 in carton stock along score line 28. This bulge terminates sharply at transverse cut line 33. The portion 35 of the fold line which is free of scoring does not have any pronounced inward bulge. Therefore, when the end wall flap 24 is infolded against the flaps 22 with locking flap 26 snugged against the main panel 16, corner 30 of the locking flap engages the end of the bulge 34 to complete the locking action of the construction described. The completed structure may be described in summary as follows: In a folding paperboard carton having a main panel 16, a side wall panel 17 connected to the main panel and an infolding end wall panel 24 with an adjoining locking flap 26 arranged to lie in juxtaposition to the main panel 16 with an edge of the locking flap closely adjacent the fold line 35 between the main and side wall panels when the end wall panel is infolded, the fold line being formed in part by scoring the paperboard stock and having a portion 35 free of scoring, this section terminating in a transverse out line 33 which is adjacent a corner 30 of the locking flap 26 when the latter is in locking position in the carton as set up for use, whereby such corner 30 of the locking flap engages the bulge 34 which forms in the scoring at the intersection of the fold line with transverse cut line 33 when side wall 17 is erected.

Fig. 4 shows the construction inside a corner of the bottom section 11 of the carton of Fig. 1 as partly set up. In this construction the part of the fold line between panels 13 and 14 which is free of scoring, is provided with a longitudinal cut line 32 terminating at the transverse cut line 29. The carton stock creates a second bulge 31 between the end of cut line 32 and the end of the carton body where the score line has been continued after interruption by the out line 32. The locking action is substantially the same as has been described with reference to Fig. 3; that is, when the end wall flap 23 in infolded against the flaps 21 with locking flap 25 snugged against the main panel 13, the corner of the locking flap 25 engages the end of the bulge 27 to complete the locking action. The detail cross-sectional view identified as Fig. in the drawings shows the nature of score line 27 following the blanking and scoring operation, and before the side wall 14 has been erected. The eifect of erecting the side wall 14 is illustrated in Fig. 7 where we see the bulge 36 produced by the inward crowding of the carton stock produced as a result of the existence of the scoring 27. Fig. 6 illustrates the condition of the stock adjacent the cut line 32. Following erection of side wall 14, we see another aspect of the bulge 36 in Fig. 8 which reveals the end locking face of the bulge where it is interrupted by the transverse out line 29.

In the modified construction illustrated in Figs. 9 and 10, the fold line between the main panel 38 and side pane1(s) 39 is free of scoring between the pair of transverse cut lines 40. When the end wall panel 44 is infolded, the corner(s) 41 of locking flap 42 engages the bulge 43 which forms in the scoring at the intersection of the fold line with the first transverse out line 40.

From the foregoing description it will be understood that any of the locking constructions we have described may be employed at either or both ends of the blank illustrated in Fig. 1, or at either or both ends of separate carton bodies or covers of other forms of boxes employing infolding end walls with flaps approximately fitting into the corner of the set up carton or cover. The terms and expressions which we have employed are used in a descriptive and not a limiting sense, and we have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall Within the purview of theclaims.

We claim:

1. A folding paperboard carton which as erected for use has a main panel, a side wall panel connected to the main panel and an infolded end wall panel with an adjoining locking flap snugged against the main panel with an edge of the locking fla closely adjacent the fold line between said main and side wall panels, said fold line being constituted in part by a score line in the paperboard stock forming an inwardly extending bead-like projection, the fold line having a section free of scoring, said section terminating in a out line disposed transversely with respect to said fold line between the main and side wall panels and which forms a locking surface in the adjacent end of said bead-like projection, said locking surface being engaged by a corner of the locking flap interiorly of the carton.

2. A paperboard carton construction as defined by claim 1 in which said section of the fold line which is free of scoring is provided with a longitudinal cut line terminating at said transverse out line.

References Cited in the file of this patent UNITED STATES PATENTS 

